Diseases and Conditions Pertaining to Livestock

The following conditions identified at the abattoir are not only related to the handling of the livestock or the product at the abattoir but are the result of a combination of factors that originated on the farm or on its way to the abattoir:

DFD in Cattle (Dark Cutting Meat)

The muscle cells in the carcass of a slaughtered animal continue living for a while by using stored glycogen for energy. This glycogen is converted to lactic acid which causes the acidity in the muscles to increase and thus the ph to fall. Normal lamb and beef carcases reach an ultimate ph after 24 - 36 hours (10 hours for pork). Without glycogen reserves to break down after slaughter, the following changes will occur:

• muscles become stiff almost immediately after slaughter
• these muscles look black
• are very firm and
• retain water

This is referred to as Dark Cutting Meat (DCM).

Dark Cutting Meat is usually identified only during the processing stage and for this reason the incidence of the problem is not always certain. International literature does however suggest that the cost to the beef industry may be as high as R20 - R30 for every feedlot animal slaughtered.

Causes of DCM

The two main factors responsible for DCM are EXERCISE and STRESS. During exercise and/or exposure to stressful conditions, animals use up their muscle glycogen. This causes the ultimate ph to become progressively higher.

The following are examples of factors that might induce DCM:

• disease
• fever
• strenuous exercise
• mounting behaviour
• fighting for social dominance of unfamiliar animals
• being put in an unfamiliar situation
• injury
• change in weather conditions
• nervous excitement

The stressors have their effect over a prolonged time before slaughter, usually more than four hours. DCM is not an all-or-nothing phenomenon and can occur in various degrees. At the same time, it is often a combination of factors leading to the occurrence of DCM. Not all animals respond equally to these stressors.

Problems Caused by DCM

Appearance: DCM appears unattractive. This dark appearance is often associated with old animals or with meat that has deteriorated.

Sensory problems: DCM has a changed flavour profile and is sticky

Tenderness: The development of tenderness during aging is markedly slower in meat with an ultimate ph between 5.8 and 6.2. Meat in this ph range will be tougher.

Spoilage: At higher ph values meat tenderization becomes very rapid, but this meat has a poor texture, poor cooking qualities and undergoes rapid spoilage.

Determination of DCM

Extreme dark cutters can be identified by the appearance and feel of the cut meat surface. Ph measurement 16 - 20 hours after slaughter accurately identifies the high ultimate ph responsible for DCM. Electrical stimulation immediately after slaughter can result in the meat reaching ph levels of 5.8 in about 2 hours.

Prevention of DCM

The following factors are important to reduce the incidence of DCM:

• Strange animals should not be mixed shortly before slaughter.
• Animals should be well rested before being presented for slaughter.
• Stunning should be effective: Similarly, the handling prior and during stunning should be in a calm manner.
• Cattle should be transported in vehicles specifically designed to prevent unnecessary stress and injuries.
• Water should always be available to cattle during the waiting period at abattoirs prior to slaughter.

Click here to view a video that explains how to reduce cattle bruising and dark cutters.

Bruising

The incidence of bruising of cattle and the consequent loss to the industry remains a serious concern to the meat industry. The really bad news is that bruises have probably stayed at the same level on a national basis during the last two decades and will remain that way unless measures exist to stop the current lack of accountability. Although the producer is currently not compensated for these trimmings, unless cattle are bought on the hoof, it is also not reflected in the payment as being condemned for this specific purpose. Surveys conducted have indicated that trimmings for this reason may be as much as 0.6 kg per carcass resulting in a loss of R 6 million rand per annum considering that part of these trimmings may be utilised for by-products if such a facility is available. Unfortunately, this is not always the case with decentralised slaughter facilities.